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Replacement with position shift

Replacement of dilorine by alkyl groups with position shift... [Pg.217]

The spectra from strong oscillators have special features which are different from those from metallic and dielectric substrates. Different structures in tanf and A are observed on a metallic substrate, dependent on the thickness of the film (Fig. 4.65). For very thin films up to approximately 100 nm the Berreman effect is found near the position of n = k and n < 1 with a shift to higher wavenumbers in relation to the oscillator frequency. This effect decreases with increasing thickness (d > approx. 100 nm) and is replaced by excitation of a surface wave at the boundary of the dielectric film and metal. The oscillator frequency (TO mode) can now also be observed. On metallic substrates for thin films (d < approx. 2 pm) only the 2-component of the electric field is relevant. With thin films on a dielectric substrate the oscillator frequency and the Berreman effect are always observed simultaneously, because in these circumstances all three components of the electric field are possible (Fig. 4.66). [Pg.272]

If at least one of the aryl groups at 3 -position is replaced with an alkyl group, then the developed color is more reddish as a result of a hypso-chromic shift. Thus, 3 -diethylamino-6 -diphenylaminofluoran (35 R = C2H5)29 and 3 -diphenylamino-6 -(/V-ethyl-/i-toluidino)fluoran (35 R = 4-CH3C6H4)29 develop reddish violet and bluish violet colors, respectively. [Pg.171]

Typical pH-activity curves obtained with gram-positive /3-lactamases and benzylpenicillin show maxima in the range of pH 6.0-7.0 with a rather sharp decline in the alkaline range (2). Recent data on gramnegative /3-lactamases (25,31, 43, 44,59,65,90,94-96) show optimal values scattered over the range of pH 5.0-8.5. A shift in the pH-activity curve has been observed when benzylpenicillin was replaced with 6-APA (78,79) or methicillin (54) but not with cephalosporin C (31). [Pg.42]

Removal (formally) of the P-furan substituents has some effect on the spectral characteristics of the oxasapphyrins. In the case of the monoxasapphyrin 5.72, the position of the Soret band of the free-base appears relatively unchanged when compared to 5.21 or 5.74. However, protonation with HCl results in a slight red-shift of the Soret bands (to 445/453 nm), while protonation with HF results in a more pronounced Soret band splitting ( imax = 436 and 460 nm). ° If two of the pyrroles of pentaazasapphyrin are formally replaced with P-unsubstituted furans (e.g., 5.68), the Soret bands of both the free-base and protonated forms of the macrocycle shift to the blue by ca. 15 nm, relative to the P-substituted dioxa system 5.75. In this latter instance, however, the Soret band does not split upon protonation. [Pg.271]


See other pages where Replacement with position shift is mentioned: [Pg.455]    [Pg.460]    [Pg.139]    [Pg.148]    [Pg.422]    [Pg.87]    [Pg.11]    [Pg.296]    [Pg.188]    [Pg.343]    [Pg.39]    [Pg.450]    [Pg.98]    [Pg.658]    [Pg.1388]    [Pg.101]    [Pg.133]    [Pg.18]    [Pg.552]    [Pg.604]    [Pg.95]    [Pg.98]    [Pg.413]    [Pg.331]    [Pg.198]    [Pg.334]    [Pg.126]    [Pg.6346]    [Pg.1801]    [Pg.489]    [Pg.57]    [Pg.2421]    [Pg.475]    [Pg.475]    [Pg.518]    [Pg.532]    [Pg.188]    [Pg.222]    [Pg.209]   
See also in sourсe #XX -- [ Pg.16 , Pg.264 ]

See also in sourсe #XX -- [ Pg.27 , Pg.212 ]

See also in sourсe #XX -- [ Pg.27 , Pg.212 ]




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Position shift

Replacement with

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